The invention relates to a method and apparatus for guiding a cast strand that is extracted from a mould and deflected into a horizontal path while its core is still liquid, by using pairs of driving rollers that are adjustable to the strand surface by pressure and by using pairs of supporting rollers whose distance apart is form-lockably adjustable.
When rapidly casting strands in continuous casting plants, a long liquid core results in the strand in dependence upon the high casting capacity, so that the guiding path supporting the strand skin must be of sufficiently great length so that the ferrostatic pressure present in the liquid core can be accommodated. Therefore, it is necessary to guide the cast strand also in the horizontal direction by pairs of supporting rollers that counteract any a bulging of the strand.
In individual cases it is also necessary to cast slowly in such rapid casting plants. This gives rise to problems, since, due to the great length of the machine which often exceeds 30 m, a lot of heat is abducted from the strand, in particular by the cooled supporting rollers arranged in the horizontal part of the guiding path. The strength of the strand increases progressively with decreasing temperatures and there is the danger that the supporting rollers will be damaged by the thoroughly solidified strand. In particular, the supporting rollers can easily be damaged by the end of the cast strand, which end is always supercooled.
It is known to install overload protection means in the form of springs or hydraulic elements in the strand guide, which allow for a swinging out of the supporting rollers in case of overload. However, when casting with high casting speeds it is very important to adjust exactly the supporting rollers that support the incompletely solidified strand, to the thickness of the cast strand, to align them precisely and to keep them in that position during the entire casting procedure in order to obtain a high quality of the strand. Resilient bearings for the supporting rollers do not meet these requirements. It is a further disadvantage that for obtaining effective overload protection the supporting rollers can be mounted only individually or at most in pairs. This requires the aligning of a very great number of supporting roller bearings against one another. This aligning of that very great number of supporting roller bearings not only causes a loss of time when the plant is adjusted to a different strand size, but is also one of the possible reasons for the increased occurrence of the misalignment of neighbouring supporting rollers.